1. Field of the Invention
The present invention relates to control of an engagement state of a clutch by actuating an actuator.
2. Description of Related Art
In a vehicle with a semi-automatic transmission that actuates an actuator to engage or disengage a clutch, the clutch is provided with a drive-side member (for example, a friction disk) that rotates upon receipt of rotational force from a driving source, and a driven-side member (for example, a clutch disk) that is pressed by the drive-side member to operate in conjunction with the drive-side member. The vehicle controls the engagement state of the clutch based on a difference in rotational speed between the drive-side and driven-side members (for example, JP-A-2001-146930). Generally, such vehicles control or gradually reduce the difference in rotational speed between the drive-side and driven-side members during engaging operation of the clutch.
The aforementioned conventional vehicle controls the engagement state of the clutch based on the difference in rotational speed during engaging operation of the clutch. This, however, can prevent appropriate torque from being constantly transmitted from the drive-side member to a downstream mechanism including the driven-side member, and thus can impair riding comfort. For example, when a half-clutch state is discontinued, torque transmitted to the driven-side member increases sharply, providing shocks to the vehicle. In order to solve this problem, another control method has been proposed, in which a half-clutch state is maintained until the difference in rotational speed is almost zero. However, such a control method can result in insufficient torque being continuously transmitted to the driven-side member over a long time period, which in turn may cause the vehicle to decelerate excessively.